/**
 * Film grain & scanlines shader
 *
 * - ported from HLSL to WebGL / GLSL
 * http://www.truevision3d.com/forums/showcase/staticnoise_colorblackwhite_scanline_shaders-t18698.0.html
 *
 * Screen Space Static Postprocessor
 *
 * Produces an analogue noise overlay similar to a film grain / TV static
 *
 * Original implementation and noise algorithm
 * Pat 'Hawthorne' Shearon
 *
 * Optimized scanlines + noise version with intensity scaling
 * Georg 'Leviathan' Steinrohder
 *
 * This version is provided under a Creative Commons Attribution 3.0 License
 * http://creativecommons.org/licenses/by/3.0/
 */

Map<String, dynamic> FilmShader = {
  "uniforms": {
    'tDiffuse': {},
    'time': {"value": 0.0},
    'nIntensity': {"value": 0.5},
    'sIntensity': {"value": 0.05},
    'sCount': {"value": 4096},
    'grayscale': {"value": 1}
  },
  "vertexShader": [
    'varying vec2 vUv;',
    'void main() {',
    '	vUv = uv;',
    '	gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );',
    '}'
  ].join('\n'),
  "fragmentShader": [
    '#include <common>',

    // control parameter
    'uniform float time;',

    'uniform bool grayscale;',

    // noise effect intensity value (0 = no effect, 1 = full effect)
    'uniform float nIntensity;',

    // scanlines effect intensity value (0 = no effect, 1 = full effect)
    'uniform float sIntensity;',

    // scanlines effect count value (0 = no effect, 4096 = full effect)
    'uniform float sCount;',

    'uniform sampler2D tDiffuse;',

    'varying vec2 vUv;',

    'void main() {',

    // sample the source
    '	vec4 cTextureScreen = texture2D( tDiffuse, vUv );',

    // make some noise
    '	float dx = rand( vUv + time );',

    // add noise
    '	vec3 cResult = cTextureScreen.rgb + cTextureScreen.rgb * clamp( 0.1 + dx, 0.0, 1.0 );',

    // get us a sine and cosine
    '	vec2 sc = vec2( sin( vUv.y * sCount ), cos( vUv.y * sCount ) );',

    // add scanlines
    '	cResult += cTextureScreen.rgb * vec3( sc.x, sc.y, sc.x ) * sIntensity;',

    // interpolate between source and result by intensity
    '	cResult = cTextureScreen.rgb + clamp( nIntensity, 0.0,1.0 ) * ( cResult - cTextureScreen.rgb );',

    // convert to grayscale if desired
    '	if( grayscale ) {',

    '		cResult = vec3( cResult.r * 0.3 + cResult.g * 0.59 + cResult.b * 0.11 );',

    '	}',

    '	gl_FragColor =  vec4( cResult, cTextureScreen.a );',

    '}'
  ].join('\n')
};
